Monday 22 October 2012 19.05 EDT
First published on Monday 22 October 2012 19.05 EDT

When a prime minister decides it is time to make a speech about crime, it is generally also time to look at the state of the polls. David Cameron made such a speech on Monday and, sure enough, the polls show his party is in trouble. The latest Guardian/ICM survey has the Conservatives stuck eight points behind Labour, 33% against Labour's 41%. The prime minister's crime speech also follows one of the most demoralising weeks for the Tories since the "omnishambles Budget" in March – a week that included the Andrew Mitchell resignation, the George Osborne train ticket hoo-ha and Mr Cameron's fumbled announcement on energy prices, all against the background of continuing economic stagnation.

Self-evidently, therefore, this was a moment that called for Mr Cameron to regain the initiative by making a tough law-and-order speech. As an admirer of Tony Blair, the PM will know his predecessor-but-one's aphorism that a leader never loses votes by being tough on crime. Many of the responses to Mr Cameron's speech saw his announcements entirely in such a frame, including the Prison Officers Association, who accused the government of playing the law and order card because it is in trouble, and Labour's Sadiq Khan MP, who dismissed it as a smokescreen.

In fact, Mr Cameron's speech is more interesting than that suggests. This is not to deny that a prime ministerial speech on crime at such a moment is one way of trying to regain lost grip. It is only fair to note, though, that Mr Cameron can hardly be accused of changing the agenda to crime when elections for police and crime commissioners are scheduled through most of England and Wales in just over three weeks. These elections are controversial. A low turnout on 15 November will be another headache for the Tories, who have promoted the introduction of PCCs in the face of almost universal scepticism, most recently from Lord (Ian) Blair, London's former police chief. It would be odd if Mr Cameron did not try to focus attention on crime at such a moment.

The striking thing about Mr Cameron's speech, however, was that it was not, overall, an old-fashioned get-tough law-and-order speech. Past leaders would have called for more spending on police, tougher sentencing and more draconian prison regimes. But Mr Cameron governs in tougher financial times. His pitch was therefore an interesting mix. It was summed up in the claim that his government was committed to a "tough but intelligent" approach through each stage of the criminal justice system. This neat piece of triangulation enabled him to celebrate, rightly, the fact that crime has fallen by 6% at the same time as central spending on police is down by 20%. It enabled him to promote an extension of life sentences at the same time as sounding more focused about the need, financially driven though it is, to boost rehabilitative options for many offenders. It was genuinely cheering to hear Mr Cameron say "we have tried just banging people up and it's failed".

In fact Mr Cameron's speech contained few new specifics. It was fairly good on strategy and rhetoric. But it was full of vagueness – the welcome denunciation of arbitrary targets sitting awkwardly with the introduction of equally arbitrary sentencing. It was silent on many of the financial and resource means without which the approach cannot succeed. Great weight is to be placed on outsourcing and payment-by-results in the private and voluntary sectors to achieve these rehabilitative goals but, as PFI showed, such systems are riddled with risk, are often inadequately drafted and tested, and can land the taxpayer with heavy costs if they go wrong.

The problem with Mr Cameron's speech was not the intentions, which were often good, but the realities, which fall significantly short of what would be needed for rehabilitation to become the truly effective alternative it must be. Shifting a party's opinion poll numbers is a hard task. But shifting the numbers in a criminal justice system that relies so much on long prison sentences is even harder.